Cellular communication networks typically employ base transceiver stations that communicate with mobile stations. When a mobile station (MS) initiates a call to the base transceiver station (BTS), it does so with an identification code. The BTS sends the identification code to a base station controller (BSC) and mobile switching center (MSC) for authentication. The MSC determines if the identification code matches one in a valid subscriber registry. Once authenticated, the BTS is authorized to communicate with the MS and the network places the call.
Ordinarily, this procedure is efficient. For example, when a MS wishes to communicate with a person at home, via land line, the mobile transmission is routed through the base station, BSC, MSC, public switch telephone network (PSTN), and then via land line to the person at home.
However, when one MS wishes to communicate with another MS, the communication is still required to route through the MSC. This type of routing is not efficient because it reserves a portion of valuable BSC, MSC, and sometimes PSTN resources for the call. Moreover, when the base station employs a transcoder rate adapter (TRAU), a private branch exchange (PBX), or other subsystems, a portion of those resources are also reserved for the call.
Hence, one limitation of existing cellular communication networks is that the BTS and BSC must always communicate with the MSC in order to place a call from one MS to another. Moreover, this routing may require a rate adaptation even when the two MS are operating at the same rate.
Another limitation of existing cellular communication networks is that they employ dedicated hardware that lacks flexibility. For example, the BTS and BSC may be required to route calls to the MSC whether this routing is most efficient or not. As another example, these networks may impose rate adaptation on all communications to match a standard rate (e.g., 64 Kbps), whether adaptation is necessary or not.
Still another limitation of existing cellular communication networks is that they lack flexibility to incorporate advanced features such as call routing in the BTS and BSC. These networks lack the ability to be scaled and modularized, and lack the flexibility to perform multiple tasks. Moreover, since existing communication networks use a great deal of dedicated hardware, a fault can cause data loss, or even cause the network to malfunction. When a BTS or BSC is broken, the network must operate in a reduced capacity, if it can operate at all.